Four types of loadings (i.e. forces) are experienced by a spot weld, namely shear, normal, peel bending, and torsion. For each loading type, there is a different test procedure to determine the individual loading limit at which the spot weld fails. In order to determine the spot weld strength, the test results for each type of loading limit are then input into a combined force based failure calculation formula in order to calculate when various combinations of these different types of loadings will cause the spot weld to fail.